Alkaptonuria (Ochronosis)

Chapter 39 discusses alkaptonuria (ochronosis), a rare hereditary metabolic disease that leads to the deposition of homogentisic acid. Homogentisic acid accumulation causes damage to connective tissues; leads to formation of renal, urethral, and prostatic calculi; causes cardiovascular abnormalities; and causes arthropathy. Ochronotic arthropathy is the articular manifestation of alkaptonuria with the most common clinical sites of involvement being the spine, knees, and hips. Diagnosis of the disease is made by demonstration of homogentisic acid in the urine. Radiography is the standard method for detecting changes associated with alkaptonuria. CT can aid in the detection of intervertebral disc calcification.